Materials Literature
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A nonracemic compound is synthesized and shown to assemble reversibly through hydrogen bonding to form a cyclic tetramer. The chiral arrangement of atoms in the individual pieces becomes amplified through self-assembly to yield multiple functional groups asymmetrically arranged within the cavity. The tetrameric capsul…
Oxidation of a graphite initiated from surface defects is investigated by using scanning tunneling microscopy (STM) and density functional (DF) calculation. The defects are created on a graphite surface with controlled depth and density by impact of Ar + ions at low energies (50−500 eV). Oxidation of the defects with…
The synthesis and characterization of divalent [Fe(TC-5,5)] (1) and trivalent [Fe(OTf)(TC-5,5)] (2) tropocoronand complexes are described. Compound 1 reacts with 1 equiv of NO to form the {FeNO} 7 complex 3 . A single-crystal X-ray structure determination of 3 reveals a trigonal bipyramidal geometry with a linearly co…
High proton conducting P 2 O 5 −SiO 2 glasses were prepared using the sol−gel method, the electrical conductivities of which were studied in relation to the pore structure and the adsorbed water. The pore properties of SiO 2 and P 2 O 5 −SiO 2 glasses were controlled by addition of formamide during the gel synthesis,…
The mechanical properties of the double gyroid (DG) cubic phase in glassy−rubbery block copolymer systems are examined. The stress−strain properties of an isoprene-rich polystyrene/polyisoprene/polystyrene (SIS) triblock and a polystyrene/polyisoprene (SI) starblock DG, both comprised of two separate interpenetrating…
Thicker-walled mesoporous MCM-41 silicas with improved thermal and hydrothermal stability were prepared via secondary crystallization (in which calcined MCM-41 was used as silica source) or by using long crystallization times. Unusually, the thicker pore walls of the as-synthesized (surfactant containing) forms of the…
Polyether dendritic compounds bearing folate residues on their surface were prepared as model drug carriers with potential tumor cell specificity. Starting from ester-terminated polyether dendrimers, hydrazide groups were easily introduced to the surface of the dendrimers by reaction with hydrazine. Folate residues we…
When Au:SR cluster compounds (R = (CH 2 ) 5 CH 3 ) with an Au metallic cluster core mass of ∼14 kDa (∼75 atoms, 1.1 nm equivalent diameter), are heated in neat dodecane−thiol solution under inert atmosphere, species with smaller Au core masses are formed, presumably by the removal of Au atoms from the outermost surfac…
We have measured the specific heat of FeS, Fe 0.875 X, and Co 0.875 X (X = S,Se) compounds with a NiAs-like structure over the temperature range from 2 to 30 K. It was found that the ground state of FeS has an insulating character. The opening up of a gap in the density of states is probably caused by electron correla…
This study was conducted to evaluate the breast skin collagen content and electrophoretic analyses of type I collagen in heterozygous naked neck and normally feathered commercial chicks. A total of 72 birds from each genotype were randomly selected at 7 weeks and slaughtered. Breast skin was separated from each carcas…
The evolution of the 5 D 0 7 F 0 emission of Eu 3+ ions in calcium diborate glasses has been analysed using time resolved fluorescence line narrowing measurements in order to give a complete view of the energy transfer processes between these ions. At low concentration (2.5 mol% of Eu 2 O 3 ) and exciting within the h…
A new experimental method for direct determination of the upconversion coefficient C(up) in Er-doped glasses is presented. This method is based on measurement of the dependence on pump power of the fluorescence quantum yield at 1.54 microm and of the excited-state absorption. Two methods are used for determination of…
Irradiation of iron with 5 MeV electrons is accompanied by the generation of point defects within small cascades, which changes the shape of the stage I resistivity recovery spectrum and stimulates the formation of di-interstitials that manifest their migration near the I D 1 substage. The specific features of stage I…
To diminish the discharge of heavy metals and lanthanides by the phosphoric acid industry, these impurities have to be removed from the mother liquor before their incorporation in the gypsum crystals. This can best be achieved by means of solvent extraction or ion exchange during the recrystallization of hemihydrate t…
Intercalation compounds of vanadyl phosphate with rubidium (Rb x VOPO 4 · y H 2 O) were prepared by reacting VOPO 4 with rubidium iodide solutions in acetone/water (volume ratio 9:1) at temperatures between 18 and 40 °C. Two phases with interlayer distance of 0.703 and 0.644 nm were formed during the intercalation; th…
Synthetic routes leading to 12 l -phenylalanine based mono- and bipolar derivatives ( 1 − 12 ) and an in-depth study of their structure−property relationship with respect to gelation have been presented. These include monopolar systems such as N -[(benzyloxy)carbonyl]- l -phenylalanine- N -alkylamides and the correspo…
Multiple crystal forms and complex melting behavior of syndiotactic polystyrene (sPS) were thoroughly examined using wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). This study has provided clear evidence for interpretation of relationships between the multiple melting peaks and polymor…
Anionic poly(ε-caprolactam), isothermally synthesized at temperatures between 155 and 195 °C by very fast carbamoyl-type activators, has been characterized by UV, DSC, and wide-angle X-ray scattering (WAXS) techniques in terms of high polymer yield, irregular structures along the chain, extent of cross-linking, T g an…
The aim of this contribution is the extension of a small strain and small deformation formulation of gradient enhanced damage to the geometrically non-linear case. To this end, Non-local Stored Energy densities, (NSE) are introduced as primary variables. Fluxes conjugated to the gradients of the NSE are then computed…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorObservation of α and γ Crystal Forms and Amorphous Regions of Nylon 6−Clay Nanocomposites Using Solid-State 15N Nuclear Magnetic ResonanceLon J. Mathias, Rick D. Davis, and William L. JarrettView Author Information University of Souther…